MILES O'BRIEN, CNN ANCHOR: Hello, and welcome from the tropical and troubled shores of Tuvalu in the South Pacific. I'm Miles O'Brien. And it's troubled because this island nation might not be here in 50 or 100 years, thanks to global warming. It would be no surprise if many of you were confused about this subject of global warming. For years environmentalists, scientists, governments and corporations have debated whether it was happening at all, whether humans were making it worse, what the effects might be, and then, finally, what, if anything, to do about it.

But now the scientific debate is largely over. There is overwhelming consensus that the threat is real, that humans are at least part of the cause, and that something must be done.

We've talked to a lot experts -- scientists who study global warming -- and you'll hear their views on how to prevent a ruined world, as one of them starkly put it.

But the story is best told in a place like this, trying to keep its head above a rising sea. Or far away from here in the Arctic, where people depend on a sheet of ice that is steadily shrinking.

UNIDENTIFIED MALE: The ice is just like our land. We live on it. We hunt from it. We retrieve our animals over it.

UNIDENTIFIED MALE: The more it warms up, it warmed up the ocean here. And it started to melt and just kept right on going.

UNIDENTIFIED MALE: A lot of what's happening is literally out of our control. We have kind of like almost no say in the process of global warming.

O'BRIEN: It may seem odd to begin a story about a warming planet in a place like this, where warmth is a rare and precious commodity, and cold is not so much a measure of mercury as it is a state of mind and a way of life.

Because here in the frozen land between the Arctic Circle and the North Pole, they don't endure the cold as much as they embrace it, rely on it for their very existence.

The ice is their land, their highway, their playground -- their supermarket. And it is slowly yet steadily disappearing into the frigid sea.

The tiny village of Kivalina, Alaska sits on a spit of land along the Arctic Circle. This is the edge of the edge. Here, houses are falling into the ocean as the coastline erodes.

The autumn ice that protects the island from brutal winter storms is coming later each year. So Kivalina is disappearing, eroding into something less than a spit of land.

O'BRIEN: The people here are considering leaving their homes to move to higher ground. This town may be in the vanguard of a global retreat inland over the coming, warmer years.

You've got to leave.

KNOX: Yes. We've got to leave sooner or later.

O'BRIEN: I'm taking a walk right now on a little piece of the Arctic Ocean. The North Pole is 1,100 miles that way, the Arctic Circle about 500 miles that way and we're just off Barrow, Alaska.

And it's kind of hard to imagine the concept of global warming here. It is below zero right now.

But up here, the warming is more of a problem than it is elsewhere. As a matter of fact, the temperature is rising here about twice as fast as elsewhere.

We are literally on thin ice. The question is, is the entire planet?

GEORGE AHMAOGAK, MAYOR OF BARROW, ALASKA: Years back when I was a kid, I used to see eight-foot-thick ice, 14-feet-thick ice. Forty years later, I'm now seeing ice, at the most, at less than two feet thick.

O'BRIEN: The ice that's disappearing literally sustains a people. It's where they hunt for food.

AHMAOGAK: We don't grow stuff up here. We don't have the money -- a lot of these people don't have the money to be able to go to the store.

KNOX: We depend on the resources. For example, there's polar bear and the seals. It's a matter of survival for our people. They're trying to now adapt to changes.

O'BRIEN: And experts say we should all be listening to what George Ahmaogak is saying.

ROBERT CORELL, CHAIR, ARCTIC CLIMATE IMPACT ASSESSMENT: There is very consistent evidence that the Arctic is warming much more rapidly than the rest of the planet, and it has significance for the rest of the world.

O'BRIEN: And this is no longer the stuff of academic debate. From a variety of scientists, we have heard the same conclusion. The jury is in. And the scientific verdict is clear.

The Earth is warming, and our addiction to burning fossil fuels is hastening the heating. Whatever debate remains focuses on how bad, how soon -- and what can be done about it.

ELLEN MOSLEY-THOMPSON, SENIOR RESEARCH SCIENTIST, BYRD POLAR RESEARCH CENTER, OHIO STATE UNIVERSITY: Temperatures of the last few decades are warmer than in any previous decades for the last 2,000 years.

O'BRIEN: Ellen Thompson and her husband Lonnie, researchers at Ohio State University, travel the world trying to figure out what the weather was like before there was anyone around to take note of it. They collect one of nature's best weather records -- ice.

LONNIE THOMPSON, SENIOR RESEARCH SCIENTIST, BYRD POLAR RESEARCH CENTER, OHIO STATE UNIVERSITY: If you look at the story from the ice, whether you look at the chemistry recorded in the ice cores, or if you look at what's happening physically to the ice on the planet, it's very clearly the planet is warming.

O'BRIEN: They drill deep into glaciers and collect masses of ice cores that are many thousands of years old, reading the seasonal layers like rings on a tree.

The current condition of those glaciers tells them much about what is going on right now -- they are melting.

The Snows of Kilimanjaro may live on -- only in fiction.

THOMPSON: Over 80 percent of the ice has been lost. And you can see that there will be no ice on this mountain by the time we get to 2015, 2020.

O'BRIEN: And all that water has to go somewhere. Scientists now believe it could mean a half meter or a foot-and-a-half rise in sea level over the next century.

THOMPSON: And now that may not sound too much unless you live in a coastal area. But if you raise sea level half a meter, you're going to displace over 100 million globally.

And the question is, you know, where do these people go?

GUS SPETH, DEAN, YALE SCHOOL OF FORESTRY AND ENVIRONMENTAL STUDIES: We're changing the face of the planet and deeply committing the future to a situation which, frankly, as a new grandparent, I am so concerned about. If we don't so something about it, we'll be handing to them a ruined world.

O'BRIEN: A ruined world. The Inuit are facing it right now.

AHMAOGAK: We're already going through this. We're experiencing the problems right now. And if nothing is done, it's just going to escalate even more further.

And it's going to be billions and billions of dollars of property loss -- not in Alaska, but also in the Lower 48, like Florida, like Louisiana and all of those areas, because the water table is coming up for sure. We see it.

O'BRIEN: Coming up, what causes global warming and how world wildlife are already feeling the heat.

O'BRIEN: They call it the polar bear capital of the world. Churchill, Manitoba, on the western banks of Hudson Bay, is probably the best place in the world for humans to catch a glimpse of the magnificent mammals that rule the Arctic icepack.

ROMANIUK: Well, last night we had four calls. One at 5:00, one at about 1:00, one about 3:00 and one at about 5:00.

UNIDENTIFIED MALE: Hey, buddy, you here by yourself?

ROMANIUK: The last three years, 2001, 2002, 2003, were the busiest years the program has ever had.

O'BRIEN: The bears are coming to town with alarming frequencies -- weak, famished and scavenging for food.

ROMANIUK: Last year there were 176 bears that were captured. About 135 were captured in and around the dump.

O'BRIEN: Polar bears are nature's ultimate binge eaters. During the winter, once the Hudson Bay freezes over, they take to the ice with a voracious appetite for seal.

They hunt and eat as much as they can get their paws on. And then when the ice gets thin in the spring, they return to terra firma for a four-month fast.

LUNN: The amount of time that bears in western Hudson Bay can spend on sea ice is critical for their survival.

O'BRIEN: Scientist Nick Lunn has logged two dozen years studying polar bears for the Canadian Wildlife Service.

LUNN: We've seen bears coming ashore in poorer and poorer condition.

O'BRIEN: Adults males are 15 percent lighter than they were 20 years ago, adult females with cubs 20 percent skinnier. The reason? The polar bear buffet is opening later and closing sooner.

Over the past three decades, the thermometer has steadily risen and the ice has just as steadily receded.

Today, the Hudson Bay returns to its liquid state three weeks earlier than it did in 1970. LUNN: They're coming ashore earlier with less fat. And they have to make that reduced amount of fat reserves last longer.

O'BRIEN: So who could blame them for coming here, searching for a snack and running afoul of Richard Romaniuk.

ROMANIUK: And a lot of people will refer to it as the polar bear jail. We don't like to refer to it as a jail.

O'BRIEN: After all, it isn't about punishment. The idea is to protect the people and the bears from each other. The bears are held here, then released when the bay freezes over.

RUSS SCHNELL, CLIMATE MONITORING DIRECTOR, U.S. NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION: Polar bears are going to be very uncomfortable when they can't have enough ice to hunt seals from. But this isn't something that hasn't happened many times in the history of the Earth.

O'BRIEN: Russ Schnell is a leading climate researcher for the National Oceanic and Atmospheric Administration.

SCHNELL: It's just that we're compressing something that happened in millions of years into hundreds.

O'BRIEN: And that's the rub.

SCHNELL: And that's the rub.

O'BRIEN: Our planet is littered with proof that pushing the fast forward button on the climate machine can mean big trouble.

Sixty-five million years ago, scientists believe a killer asteroid struck the Earth, kicking up the mother of all dust storms. The sun's rays were blocked, plants and trees died en masse. And before too long it was curtains to the dinosaurs.

Ironically, it was that event that laid the groundwork for the climate change issue we're dealing with today. When the dust settled, the path was clear for mammals and, ultimately, humans to dominate the planet and eventually go on to burn large amounts of fuel derived from the fossils of those dinosaurs.

And burning fossil fuels creates carbon dioxide. Russ Schnell likens the effects of CO2, along with the other greenhouse gases, to a featherbed.

SCHNELL: So if you can visualize laying in a featherbed and continually adding feathers, eventually you're going to get an extra inch or two, and your heat is going to be retained. And that's exactly what's happening to the Earth.

O'BRIEN: And the feathers -- carbon dioxide and all the other greenhouse gases -- are very stubborn. They just sit in the air up there. And they act an awful lot like panes of glass in a greenhouse. They allow the solar energy in, but they still trap the heat that is radiated back from the planet.

SCHNELL: Even if we stop producing CO2 today, the effects would last for a couple of centuries.

O'BRIEN: Where there is fossil fuel smoke there is heat, if not fire. Here's the verdict from a United Nations report signed by more than 2,000 scientists from around the world. Most of the warming observed over the past 50 years is attributable to human activity.

SCHNELL: We're going into this huge experiment, not really knowing where it's going to end.

O'BRIEN: Climate change is not new, but this time it is different and it is happening fast. And unlike the dinosaurs, we can do something about it.

But will we, before the polar bears of Hudson Bay go the way of T. Rex?

LUNN: There's going to be a point in time where the bears are forced ashore so early that they just simply won't be able to survive.

MILE: When we return, a small nation that may be swept away.

UN: We feel anxious. Where are we going to go?

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O'BRIEN: It's not so much a nation as it is an extended family, living in many layers of harmony.

PAANI LAUPEPA, ASSISTANT SECRETARY OF FOREIGN AFFAIRS, TUVALU: Our culture is unique -- the way we live our lives, the way we look after our children, the way we dance, the way we sing.

O'BRIEN: But beneath the unbridled joy of this community crescendo they call a "fatele," the people of Tuvalu are tugged by an undertow of fear.

LAUPEPA: We feel anxious. Where are we going to go? How are we going to survive in a totally new environment?

O'BRIEN: The very sea they celebrate in song and dance, out of the clear blue now threatens everything they know and love.

LAUPEPA: We are coming to the realization that this is not going to last forever.

O'BRIEN: Miles from nowhere, halfway between the Solomons and the Samoas, the islands of Tuvalu are little more than nine coral heads barely treading water in the South Pacific.

LAUPEPA: You cannot stem the tide, really. There's no way you can stem the tide.

O'BRIEN: And therein lies the problem.

A changing climate means a rising sea. And there's no way to rise above global warming here. Most of Tuvalu sits little more than six feet above mean sea level.

In a few generations the islands may sink beneath the waves.

LAUPEPA: There's no high ground to move to. And for us it's a matter of survival.

O'BRIEN: Well, you grew up here.

Paani Laupepa is the nation's assistant secretary of foreign affairs. Like most everyone here, he has lived in Tuvalu by the sea nearly all his life.

He doubts his four young children will be able to do the same.

LAUPEPA: Eventually we will be forced to move from this place, will be forced to move through no fault of our own.

O'BRIEN: While there is a natural fluctuation in sea levels, here the trend has been up for as long as they've been able to measure it.

The signs are everywhere.

These crops here have been abandoned. Why have they been abandoned?

UNIDENTIFIED MALE: They have been abandoned because of salt water intrusion. That means the hard labor that the farmer is putting into the crops is wasted.

O'BRIEN: During high tides, even moderate waves become shore- battering threats. And big swells can easily swamp a neighborhood.

It looks like I'm trudging through a puddle that is left after a big rain storm, but it isn't. You've got to taste the water to be sure. It's salty -- sea water. This is a high tide. As a matter of fact, it's one of the highest tides of the year. They call them here on Tuvalu, king tides.

And if you look over here you can see what's happening. The water is literally oozing up from underneath. This island is flooding from the inside out.

Six thousand miles away in Boulder, Colorado, scientists are watching what is happening in Tuvalu -- and everywhere else, for that matter -- trying to understand climate change from the inside out.

BILL COLLINS, CHAIR, CLIMATE SYSTEM MODEL, NATIONAL CENTER FOR ATMOSPHERIC RESEARCH: To do one day takes us about three trillion arithmetical calculations. O'BRIEN: One day is three trillion calculations.

COLLINS: That's right.

O'BRIEN: Wow.

Created and constantly refined by more than 300 scientists all over the world, the model here at the National Center for Atmospheric Research factors in temperature changes all over the Earth in 10- minute increments for the past 10,000 years.

COLLINS: This is the temperature in 1892. And it's a little cooler than present days.

O'BRIEN: It is the basis for a stark forecast.

COLLINS: And now we're going to start marching forward in time through this Second World War here, come up to just about present day. And this is where we're projecting the future.

So, marching through the 21st century, you can start to see the warming, for example, up in Eurasia, the warming particularly up here in Canada and western United States.

O'BRIEN: A decade in the making, this model and about two dozen others like it, consistently and unequivocally predict the planet will warm up anywhere between three to eight degrees Fahrenheit in the next century.

And that could mean longer and more severe heat waves, droughts, coastal flooding, crop failures and wild weather patterns.

COLLINS: You can argue about whether or not the change will be larger or smaller. But all the models say it's warming, and that we are definitely changing the chemistry of the atmosphere in a way that is historically unprecedented.

O'BRIEN: Collins and his colleagues readily admit the shortcomings of their daunting effort to distill the workings of the world into silicon chips.

O'BRIEN: Richard Lindzen is a climate scientist at MIT and a longtime critic of global warming modeling.

LINDZEN: People seem to have a good reason to understand that forecasting weather is inaccurate beyond two or three days.

Why one should believe that a forecast 40 years ahead, or 100 years ahead, will be better is not clear to me.

COLLINS: We believe the evidence will ... O'BRIEN: Even when scientists look back there is debate. This graph of 1,000 years of northern hemisphere temperatures is the latest skirmish.

It is one of a number of studies that make the case for global warming. While it shows temperatures rising dramatically during the past 100 years, there are some who say it is based on faulty math.

The vast majority of scientists say they know the evidence of warming is clear. Even the Pentagon has taken the threat seriously.

War planners have drafted a worse worst-case scenario report that paints a grim picture of an unsettled world -- several major refugee crises, a serious shortage of food and fresh water, disruption, instability and war.

It is doomsday stuff, but it is a real concern.

SPETH: The developing countries don't have the resources to do even the modest adaptations that we might be able to make here.

O'BRIEN: None of this is news in Tuvalu, where the per capita annual income is about $1,000. But even if the people here find another home, can what is special about Tuvalu live on if the land is erased from the map?

UNIDENTIFIED MALE: You're being forced to move because someone else in the United States, someone else in Europe, someone else in Canada is living a very good life. He doesn't give a damn about what's happening down the track.

O'BRIEN: Next, the threat to the U.S., the city in the crosshairs of global warming.

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O'BRIEN: In the marshy bayous where the mighty Mississippi rolls and roils into the Gulf of Mexico, the water is rising, the land is sinking and a way of life is gradually fading away.

KEN CAMPO: In 1960, this channel marker right here was 40 feet on land. Now, as you can see, it's no longer on land. None of the markers are land.

O'BRIEN: Kenny Campo (ph) is as much a creature of the bayou as the wild game he has pursued here most of his 56 years.

CAMPO: Muskrats, otters, nutrias, minks. We trapped all of that on here, but we're losing it. It's gone.

O'BRIEN: Gone, along with the marshes that sustain his prey, swallowed up by the muddy waters of the big river. Where there was once 14,000 square miles of marsh and swamp, there is now half that much.

PROF. BOB THOMAS: We loose about a football field size about every 30 to 40 minutes.

O'BRIEN: Professor Bob Thomas is chair of environmental communications at Loyola University in New Orleans, the city the United Nations has called the most vulnerable to the effects of global warming in North America.

THOMAS: If you live in Dover, England, and you go out and look over the edge and you look down this big cliff and you say, well, the water's going to come up six and a half inches in the 50 years or maybe even 10 inches in the next 100 years. It's not a lot of concern. But if you live in coastal Louisiana that's like this...

O'BRIEN: Louisiana is so vulnerable, because of a special problem. Hundreds of years of carving up and walling off the Mississippi delta to suit human needs has made the terra not so firma. And now much of bayou country is already sinking. Global warming will make it worse.

THOMAS: So literally, you could come up with anywhere from 21 to 44 inches of relative sea level rise in the next 50 to 100 years.

O'BRIEN: Big numbers in a place that is home to big numbers. Two million people live in coastal Louisiana. But slowly, quietly, people are leaving the places they love, places like Shell Beach, where an old fishing community has dwindled to a handful of fisherman.

THOMAS: We haven't seen any cities where people had to move yet, but there are several of them in Louisiana that I would believe in my children's lifetime will have to be relocated. It's going to be a massive relocation effort.

O'BRIEN: Now think globally for a minute. Consider the millions of people all over the world who live near the sea.

LONNIE THOMPSON, SENIOR RESEARCH SCIENTIST, BYRD POLAR RESEARCH CENTER: I think this is the thing that really makes our world so much different than in the past when we had natural variations in things like sea level. We never had 6.3 billion people and we never had millions of those people living right at sea level.

O'BRIEN: Thirteen of the 17 largest cities in the world sit right on the water. Jakarta, Bombay, Hong Kong, Tokyo, New York, Los Angeles. So why are the seas rising? It's not as if the icebergs that are currently in the ocean are melting. That would be no different than this glass. If the ice melts, it doesn't cause this cup to runneth over. No, the ice that is the problem is the ice that is on land, in this case, the ice bucket. Add some ice to the drink and very quickly, you've got a big mess. In the case of the planet, the ice bucket is Antarctica.

RUSS SCHNELL, CLIMATE MONITORING AND DIAGNOSTICS LAB, NOAA: That's where the real ice is. People may not realize that there's two miles of ice in Antarctica. That's two miles, not two feet, two miles thick. That's a lot of ice spread over a huge area. If and when that starts breaking and moving out and melting, then you're going to see sea level changes. O'BRIEN: So what if the seas rise a foot-and-a-half over the next century? What will be the cost to us all? The UN estimates somewhere between 20 and $150 billion in property damage in the U.S. alone, but that figure doesn't tell the real story.

THOMAS: The resources won't be here and people will not be living their lives the same way and that will be a tragedy.

O'BRIEN: And from Kenny Campo, the loss of a way of life.

CAMPO: What is a man 60-years old going to do? Somebody going to hire him, that he's been a fisherman all his life. No. So he stays fishing. He makes a living at it, but his kids, his grandkids are moving out. We're losing our future.

O'BRIEN: When CNN PRESENTS returns, who funds the debate over global warming?

ROSS GELBSPAN (ph), GLOBAL WARMING ACTIVIST: And I thought these people were basically stealing our reality.

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SPETH: We've known about it since the late 1970s and we've done very little about it. So a quarter century has passed, a quarter century of neglect of knowledge, a neglect of the climate change and now we are faced with a real crisis situation.

O'BRIEN: So why has the response to climate change moved at such a glacial pace? Well, at least in part, it's because scientists weren't so sure about their theories. That led to a drawn-out debate over the last two decades over whether the threat was real. It's a debate that left many people confused, but there are critics who say that confusion was deliberate.

GELBSPAN: This is just a recent list of what ExxonMobil has spent in 2003.

GELBSPAN: I sort of got sucked into being a crusader. I sort of moved from being a journalist to an advocate to an activist.

O'BRIEN: Ten years ago, Gelbspan, a retired "Boston Globe" editor, was researching a piece on global warming for the "Washington Post." He quickly became outraged at what he learned.

GELBSPAN: Greenhouse skeptics whose work I read were being very dishonest. They were being very selective in what data they were using. They were manipulating information. And I thought these people were basically stealing our reality.

O'BRIEN: So he began writing it as he saw it. He's now published two books on climate change. His latest, "Boiling Point," documents coal and oil companies bankrolling some scientists he calls greenhouse skeptics.

GELBSPAN: For the longest time, the fossil fuel lobby spent huge amounts of money on a very pervasive campaign of deception and disinformation which was designed to persuade the public and policy makers that this issue was stuck on uncertainty.

O'BRIEN: Gelbspan says the industry campaign obscured the growing consensus among scientists. Beginning in 1990, a series of United Nation's studies authored by more than 2,000 of the world's leading researchers, concluded climate change is real and that human use of fossil fuels is the primary culprit. Many energy companies have accepted the consensus, but Gelbspan charges the largest of them all, ExxonMobil, continues to fuel the debate.

GELBSPAN: ExxonMobil has spent something like $5 million over the last four or five years funding these naysayers.

O'BRIEN: We asked ExxonMobil about Gelbspan's claim but the company declined CNN's request for an on camera interview. In a written response to questions, Exxon said it had taken action to improve energy efficiency and reduce emissions at its plants. The company did not directly answer the charge that it had deliberately funded skeptics to confuse the debate, but said, we are convinced that climate change could pose a serious risk, both to society and to ecosystems. We are also convinced that climate science contains significant well-documented gaps and uncertainties that continue to limit society's ability to predict what changes may occur.

PATRICK MICHAELS, PROFESSOR OF ENVIRONMENTAL SCIENCES, UNIVERSITY OF VIRGINIA: We have had many apocalypses through the ages that haven't shown up and this is likely to be another one.

O'BRIEN: Patrick Michaels is one of the researchers who has received funding from the fossil fuel industry, more than $150,000 worth. But he says it's a small percentage of his total funding. That has to taint everything you say, doesn't it?

MICHAELS: I actually believe that there's a document called the Constitution in the United States and I haven't read in there, that only the Federal government can ask a research question.

O'BRIEN: Michaels says many climate scientists have exaggerated the threat of global warming because in Washington, that gets you dollars.

MICHAELS: Issues have to be portrayed in stark and dire terms. Nobody ever got big programmatic money out of this town by saying well, my issue might not be a problem or yeah, there are probably some overblown aspects of this issue. You'd get booted out the door immediately.

O'BRIEN: Michael's position is in the minority. The consensus is the scientific debate is all but over.

SPETH: The compelling science on this issue has been accumulating rapidly, like a big snowball going down the hill. It is overwhelmingly compelling. In many cases, the same personalities have been the critics for this almost 30 years now. They are so isolated at this point as to be irrelevant. The issue really has shifted from the scientific debate to an economic debate and an equity debate.

O'BRIEN: And that debate is also responsible for the foot dragging in response to climate change. In 1997, world leaders gathered in Japan to draw up what would become the Kyoto Protocol, a pledge to forcibly reduce greenhouse emissions. By the time it went into effect early this year, more than 140 countries had ratified the treaty, but President Bush opposes Kyoto. The U.S., along with Australia, are the only large industrialized countries to do so.

GEORGE W. BUSH, PRESIDENT OF THE UNITED STATES: It would have cost our economy up to $400 billion and we would have lost 4.9 million jobs.

O'BRIEN: The administration insists the cost of Kyoto is too high, the science uncertain and that the agreement lets countries with developing economies off the hook.

BUSH: The world's second largest emitter of greenhouse gases is China, yet China was entirely exempted from the requirements of the Kyoto protocol.

O'BRIEN: Whether or not the exemptions are fair, world leaders condemn the U.S. for its stand, even some industry leaders have joined the call for action.

JOHN BROWNE, CEO, BP OIL: There is a case for proportionary action on climate change because the evidence is strong.

O'BRIEN: John Browne, chief executive of BP, has made waves at the fossil fuel industry by calling for limits on production of carbon dioxide.

BROWNE: The real risk is to do nothing, and then to find that reality has crept up on us and that urgent, drastic action is necessary and that really does cause economic damage.

O'BRIEN: BP, one of the world's largest oil companies, is now also one of the biggest sellers of solar powered systems. And even Exxon is less strident. The company is now funding research into technologies that reduce greenhouse gases to the tune of $100 million. But the argument over what to do and what it will cost goes on. The bottom line, the choice may be an economic cost today or an environmental cost tomorrow.

SPETH: Can we prevent all damages from climate change? No. We're too late. We missed that boat, but we can certainly prevent the worst things from happening. This is our last chance to get it right. We have run out of time.

O'BRIEN: When we come back, what to do about global warming.

SEN. JOHN McCAIN, (R) ARIZ: Voluntary measures are nice, but they're not being taken. The private sector is going to figure out how to do it best.

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JACK MARTIN: I wanted to go just all the way, I mean the whole nine yards. We wanted to just be the greenest house ever built.

O'BRIEN: Think globally, act locally. At the Martin house in Mooresville, North Carolina, they take that bumper sticker expression to heart.

MARTIN: I'm definitely a green person, but I'm not a fanatic.

O'BRIEN: But Jeff Martin sure does have a fanatical eye for detail.

MARTIN: The windows are the highest R value that you can get.

O'BRIEN: Everything about this place, from top to bottom, from cells to cellar, is designed to wean the house from burning fossil fuels.

MARTIN: For the most part, we've done everything that you can do green in this house.

O'BRIEN: Solar thermal panels on the roof provide all the heat and hot water and there's some that can generate electricity. There's also a geothermal heat pump, clever placement of windows, thick insulation and plenty of power-stingy appliances. Still, this is not "Little House on the Prairie," not by a long shot.

MARTIN: We still have a large-screen TV. We have computers. We have all those things, so you don't necessarily have to trade off on those things.

O'BRIEN: Sunny, spacious, all the comforts. For the Martins, it is home green home. It costs a lot of green though, about 15 to 20 percent more than they would have paid for a plain old fossil fuel thirsty home.

MARTIN: We have 12 different heating zones in the house.

O'BRIEN: But for the Martins, the benefits of living here are priceless.

MARTIN: The intangibles are knowing that you're trying, even our small way, to do the right thing, to try to take a lesser bite out of the planet.

O'BRIEN: Just one family, just one small bite, but while the technology and efficiency of solar, geothermal and wind power improves, there still aren't many American utilities willing to invest in a big way in green energy. Today, the U.S. gets lets than 10 percent of its energy from renewable sources.

And there are other potentially effective ideas out there that private industry is reluctant to pursue on its own because of the cost, big ideas like taking carbon from smokestacks and burying it in the ground, rather than putting it in the atmosphere.

MCCAIN: Voluntary measures are nice, but they're not being taken. We have to provide some incentives for them to be taken.

O'BRIEN: Arizona Senator John McCain is among lawmakers who suggest the road to a solution to global climate change is paved with government intervention. He wants to force industry to act with a bill that would set caps on emission of greenhouse gases.

MCCAIN: It's not an Earthshaking or huge proposal, but it's an important one and it would be an important first step in trying to control the increase in greenhouse gases.

O'BRIEN: McCain would also like to see the government force Detroit to build more fuel-efficient cars and create incentives for industry to turn to clean energy sources.

MCCAIN: None of those things is the administration doing vigorously. I've never heard a single administration official say that this is a top priority.

UNIDENTIFIED MALE: We're not putting our heads in the sand in this one.

JIM CONATIN (ph), BUSH ADMINISTRATION: Not at all, not at all.

O'BRIEN: Jim Conatin is the Bush administration's point person on climate change and from where he sits, regulation is not the answer.

CONATIN: The private sector is going to figure out how to do it best in a way the government probably couldn't and we should enable them to innovate and find those solutions the government's incapable of figuring out faster.

O'BRIEN: The concern is the economy, that burdening U.S. industry with regulation would mean a loss of jobs. But John McCain believes the caps, the regulations and the incentives for new technologies are not only good for the environment and the climate, they are good for businesses as well, a jobs creator in new high-tech industries.

MCCAIN: When it requires the leadership of the administration, I think we can prove that development of alternate technologies can be a very profitable business.

O'BRIEN: But Conatin says the private sector doesn't need a nudge from the government.

CONATIN: We want to encourage them to find the most economically profitable ways to reduce greenhouse gases and we do not yet need to take on an issue, whether we need to impose a cost on our society to find those gains. We can cross that bridge if we need to when we come to it. Fortunately, we still have time ahead of us and time is on our side. O'BRIEN: But is it really? Ask the people of Kivalina (ph) on Alaska's west coast. Their island is being swept away by something that is way beyond their control and the only reasonable solution for them is a Draconian one, pack up and leave their homes behind. Are you worried about what's happening to the planet, though?

UNIDENTIFIED MALE: Yes I am. Yes, it's changing too fast.

UNIDENTIFIED MALE: Even though it has not affected a whole lot of people, it probably will eventually. I think this is kind of the first signs of global warming. More people need to pay attention to what's happening here.

SPETH: There's so much that we can do and if we get serious about it now, we can head off the worst things. We don't have to live in a ruined world.

O'BRIEN: Sadly, human history is most frequently a story of conflict, of how the people of our planet can't seem to get along. Any real solution the problem of global warming will force us all to rise above that in order to agree on a course of action. This is not a problem that can be solved by a single nation and that is an unprecedented challenge to us all. Are we up to that challenge? How will this chapter of human history be written? The plight of Tuvalu might be easy for us to forget or ignore and perhaps that is human nature, Tuvalu and Kivalina, Alaska may not seem like your back yard, but maybe we should all think of them as if they were. Thanks for joining us. I'm Miles O'Brien. Join us again next week for another edition of CNN PRESENTS.

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